Stratified primer charge



Jan. 19, 1937. F. R. sEAvEY STRATIFIED PRIMER CHARGE `l'iled July 14, 1933 l. yffffffferflfffff/ 6 I Oil! rlfflffffllffffll Patented Jan. 19, 1937 PATENT" ol-FlcE '2.068.516 sraarir'mn ranma CHARGE Frederick R. Seavey,

Western Alton, lll., assigner to Y Y. e Cartridge Company, East Alton, Ill., a

corporation of Delaware Application July 14, 1933, serial No. 680,347

13 Claims. 'I'his invention relates generally to primers,

' and particularly to a process of making primers for ammunition in which the necessary quantity of initiator is substantially reduced.

In primers of the type generally employed in small arms ammunition, and particularly with primers of the anvil type, it is apparent that only that portion of the initiator which is eiTective in initiating the ignition of the composition is that portion which is disposed so as to be acted upon by the detonating blow or initial action of the iiring pirrY or striker blow transmitted through the metal of the primer cup, or in the case of primers of the stab-type (anvilless) (open or metal foiled) to the initial acgion of the penetrating firing pin. For instance, with primers of the anvil type, it is apparent that the ignition of the priming mixture is 1nitiated by the action of initiator which is disposed immediately adjacent theanvil point and the primer cup. It

has been the general practice heretofore to incorporate an initiating ingredient throughout a priming mixture comprising other constituents, such as sensitizers, oxidizers and fuels, and to dispose such a mixture within a primer cup for action of a ring pin or anvil, but in view of the fact, however, that a relatively small quantity of initiatorI may be so placed that it will be acted upon by the detonating blow and will be 'capable of initiating the detonation, it is an object of the present invention to provide an arrangement of ingredients in a primer which will result in a vsubstantial saving of theA more expensive initiator.

The object of the present invention, generally stated, is to provide a primer in which the quantity of initiating ingredients employed is reduced to a minimum.

Another object of the invention is to provide a primer in which alhighly sensitive mixture is exposed directly to the action of a detonating blow while a less sensitive mixture is disposedto be ignited by the-initiator.

A further object of this invention is to provide a primer composed' of' increments of at least two priming mixtures, so disposed that the more sensitive increment is subi impact, the less sensitive increment ignited by the detonating or burning, or both, of the initiating mixture, and that the combined action of both'will function the next unit in the ignition or explosive train of the article in which the primer may be used.. A

A further object of the invention is to provide oi a relatively small volume ected to initiation by (Cl. 10B- 18) a primer in which the ingredients are so arranged that excessive pressures will be avoided, but proper ignition of the propellant charge accomplished.

Other objects will become apparent to those 5 skilled in the art when the following description of several illustrative embodiments is read in connection with the accompanying drawing.

It is to be understood, however, that the invention is not limited to the particular embodiments 'which are hereinafter specically described for the purposes of illustration, but that the present invention is susceptible of use in primers generally and Without regard to the particular ingredients which enter into the 15 priming composition.

In the accompanying drawing:

Figure l is a, sectional view showing one arrangement of primer strata in a typical anvil primer assembly.

Figure 2 is a similar view of another arrangement.

Figure 3 is a similar view of a further embodiment.

a still further Figure 4 is a similar view of embodiment.

In accordance with the present invention the sensitive ingredient of the priming composition is so located in the primer cup, and particularly with reference to the point of the anvil that the quantity of initiator necessary to properly prime the ammunition may be substantially reduced. The present invention contemplates that the initiating substance, whether used alone or mixed with other ordinary priming ingredients, be concentrated in a region adjacent the point of the anvil and in the bottom of the primer cup so as to receive the detonating blow. A relatively small quantity of initiator or composition containing the initiator is suilicient to ignite a fuel ingredient capable of producing suitable heat and ame. Accordingly the sensitive increment containing the initiator may be Nc vered or surrounded by what will be referred to as a relatively insensitive increment which may containsuitable heat and llame producing ingredient. The secondary or insensitive increment may -be of the same composition as the sensitive increment except that the initiating ingredients may be eliminated, or may be of entirely diier- 5o ent composition depending upon the characteristics desired. The relatively sensitive and relatively insensitive increments or strata may be arranged in any number of various ways, and for the purpose of illustration will hereinafter be s described. It is a. feature of particular advantage of the present invention, however, that the entire priming charges do not necessarily contain the highly sensitive, more costly initiating ingredient, but such of the initiating ingredient as is employed as disposed where its effect will be greatest. Likewise the use of customary abrasive sensitizers such as glass becomes unnecessary, except in that increment which is to re'- spond to the detonating blow of the firing pin.

AIn view of lthe fact that the sensitivity of the secondary mixture to friction or impact, such as is produced by a' detonating blow of a. firing pin is immaterial, it is apparent that a suflicient quantity of suitable binder may be so incorporated with the fuel and oxidizing ingredients to render the mixture completely waterproof. Accordingly when the initiating mixture is covered with a layer of secondary mixture in which a waterproofing binder is incorporated in excess of the percentage of waterproofing binder incorporated in the sensitive mixture the whole will be rendered more waterproof without interfering with the sensitivity of the primer.

As used throughout this description the word initiator will be understood in its ordinary 4 sense as contemplating the highly sensitive priming ingredients, such for instance as mercury fulminate, lead azide and the like. The word oxidizer will be understood in its ordinary sense as meaning such materials as potassium chlorate, barium nitrate, and the like. Likewise the word fuel is used in its ordinary sense in this art as contemplating readily combustible substances, such for instance as antimony sulphide, lead sulphocyanate, ferro silicon, aluminum, zirconium, nitrosoguanadine, guanadine picrate, and the like. "I'he features of the. present invention are applicable alike to the loading of either wet or dry mixtures although in the following descriptions there is described no specic embodiment in which the mixture is loaded dry.

A conventional battery cup assembly is illustrated in the drawing and may comprise a battery cup I receiving in one end thereof a priming cup\ 2 adapted to contain the priming composition and receive the detonating blow from the ring pin of a weapon. Disposed onv the inside of the battery'cup may be an anvil 3 having a point 4 extending into the region of the priming cup. In the end of the battery cup I which extends into the region of the propellant charge may be an opening 5 through which the flame may be propagated. If desired, a suitable covering,gas for instance a piece of metal foil 6 may cover the opening 5. The primer assembly illustrated in the drawing and described above is illustrative of a conventional type, but it will Abe understood that the features of the present invention are not limited to use in connection with such assemblies but are applicable to primers generally.

AAs a specific illustration of such a primer,

Figure 1 shows a stratified arrangement wherein Il may be of the same composition as pellet I0, but without the initiator.

As illustrated in Figure 2 `of the drawing the secondary or insensitive increment is in the form of an. annular ring f2 which may be formed in the primer cup as shown. In the central opening of the ring I2. may be placed a -plug I3 of composition containing the initiator which has been heretofore described as a sensitive or prim- Y ing increment. As clearly shown in Figure 2 the point 4 of the anvil extends into the sensi- -tive mixture I3. It may be advantageous to incorporate a waterproofing binder in the composition of plug I3. The use of 1-21/2% ester gumin either or both increments improves the stability and dependability of the primer without substantial reduction of the sensitivity.

A further illustrative embodiment is shown in Figure 3 and may be charged as follows; a suitable initiator, such as for instance lead azide, and, if it is desired, a suitable sensitizer such as glass, may be suspended in a suitable vehicle. such as for instance a solution of gum arabic and dichlorethyl ether, and as many drops of the suspension as is desireddropped directly into position in the primer cup and preferably adjacent the point ofthe anvil as shown at I4. By thus forming a. suspension of the initiating mixture it may be readily placed in the desired position in the cup as by dropping. Although the presence of such a binding material as gum arabic or Canada balsam is not to be regarded as necessary, such binders, nevertheless, facilitate in the handling of the materials and maintain the same in position in the primer cup during the subsequent loading. After the initiating mixture has been thus placed in position a suitable secondary mixture I5 preferably containing a fuel ingredient and an oxidizing agent may be placed in position in the cup and covering the initiating mixture.

' the center of the cup, and in position which will be adjacent the point of the anvil 3. Over the glass may then be deposited a drop of initiator I8, such for instance as lead azide in suspension and this then covered with a secondary mixture I9 as described above.

From the foregoing 'description it is apparent' that when various ingredients of a priming mixture are arranged in strata or layers in a primer cup with a small quantity of initiator in a position for direct action of a detonating blow, such as for instance immediately adjacent the point. of the anvil, a substantial economy of the more highly priced initiating ingredients is rendered possible by reduction in the necessary amount thereof. By thus reducing the amount of initiator employed excessive pressures in`\. the primer cup, or shall, which have heretofore been experienced with violent initiators may be avoided. At the same time, however, proper ignition of the propellant charge may be assured by increasing the amount of heat or-ame producing ingredients without aiecting the sensitivity.

It is apparent that by thus arranging the va.- riousingredientsofaprimirigmixtureinthe strata, or increments. it becomes possible to employ materials in the priming mixture which, although useful together have heretofore been regardedA fas incompatible in the same mixture because\ \oi`y the danger of reaction. By using immisciblejrjbinders and solvents in the different strata lthe incompatiblel ingredients will be maintained in segregation without danger of reaction. Furthermore when a secondary charge. containing for instance a fuel and oxidizer, is superimposed upon or smrounds an initiating mixture in the manner hereinbefore described,

it is apparent that complete waterproofing of' the entire priming mixture is rendered readily possible. 'Ihis has heretofore been generally regarded as impossible, particularly for the reason that waterproofing agents generally operate as deterrents and thus generally decrease the sensitivity of the initiating ingredients to which they might be exposed. With an arrangement such Vas hereinbefore described, it is apparent. however, that the use of higher percentages of waterproofing material may be confined to the secondary charge which preferably contains no initiating substances and accordingly thesensitivity of the primer will be unimpaired by the use of waterproong binders. Moreover, in View of the high percentage of initiator in the sensitive in- -crement the waterprooiing material may be incorporated in it also without seriously affecting its operation.

From the foregoing description it is apparent that many modifications of the arrangement of the priming ingredients in a priming cup hereinbefore described will present themselves to those skilled in the art without departing'from the spirit of the invention. It is to be s pecically understood. therefore, that the invention is not limited to the specic details hereinbefore setforth, and that such individual features and sub-combinations of features as do not depart from the spirit of this invention are. although not 'specifically described herein, contemplated by and within the-scope of the appended claims.

Having thus described the invention what is claimed is:

1". In a primer havingan anvil, the combination comprising, a relatively small quantity of sensitivepriming mixture containing suiilcient of an initiator to produce desired sensitivity characteristicsr for the primer disposed adjacent the anvil point, and a less sensitive layer condizing agent arranged as a ring around the plug.

3. A charge for an anvil primer comprising, a plug of sensitivel primer composition adjacent the point of the anvil.' and a ring of relatively insensitive but explosive composition surrounding the plug in adjacent relation.

4. `A charge for an anvil primer comprising,

` a plug of sensitive primer composition 'adjacent to the point ofthe anvil and a ringof relatively insensitive 'composition surrounding the plug in adjacent relation.

5. A primer charge comprising a plug of sensitive primer composition centrally located, and a ring of relatively insensitive composition encircling theplug in adjacent relation. 6. A primer comprising, a sensitive increment of priming composition containing an initiator disposed to be acted upon by a detonating blow, and a relatively insensitive increment of the same ingredients as the first except that it is substantially devoid of initiator, said insensitive increment arranged to be ignited by the sensitive increment.

7. In the art of making primers the process comprising, suspending a priming composition containing an initiator in a vehicle, and dropping the suspension of initiator and vehicle into position in a priming cup.

8.In the art of making primers the process comprising, suspending a priming composition -containing an initiator in a vehicle, dropping the suspension of initiator and vehicle into position in a priming cup, and covering the dropped suspension with a secondary mixture containing a fuel and an oxidizer.

9. In the art of making primers the process comprising, suspending a priming composition containing an initiator in a vehicle, dropping the suspension of initiator and vehicle into position in a priming cup, and covering the dropped suspension with a secondary mixture containing a waterproong binder.

10. In the art of making primers the process comprising, iixinga sensitizer in the primer cup, coveringthe sensitizer with an initiator, and covering the intiator with a mixture containing a fuel and oxidizer. A

11. In the art of making primers the process comprising, fixing a sensitizer in the primer cup, covering the sensitizer with an initiator, and covering the initiator with a mixture containing a fuel and an oxidizer in a waterproong bin'der.

12. In a primer having an anvil, a relatively small sensitive increment disposed adjacent the point` of the anvil to be acted upon by a detonating blow and comprising an intiator. a fuel and an oxidizer, and a second increment disposed for ignition by the sensitive increment and containing a fuel and an oxidizing agent, said sensitive increment being so constituted as to produce the desired sensitivity characteristics of the primer and' said second increment being so constituted as to produce the'desired heat and name characteristics of the primer.

13. In a primer having an anvil, a charge for the primer comprising initiator-containing-compomtion situated at the point of theV anvil and to be fired by the firing pin impact, and a fuel-oxidizer mixture relatively insensitive to impact or friction, disposed for ignition by the sensitive composition, said initiator-containingcomposition being so constituted as to produce the desired sensitivity characteristics of the grimms;- independently of said fuel-oxidizer mix- 

